Noun phrases usually need a framing element. A determiner is a word that introduces a noun and specifies aspects of reference such as definiteness, quantity, possession, or proximity.

Articles, demonstratives, possessives, and quantifiers commonly serve as determiners. In English a determiner typically precedes adjectives and the noun. Some languages allow determiner stacking; others restrict the slot tightly or lack a dedicated class.

Determiners interact with noun semantics and information structure. Learners must sort out subtle contrasts among quantifiers and articles. Many syntactic theories treat the determiner as head of its own phrase.

• Word that specifies noun-phrase reference
• Includes articles, demonstratives, quantifiers
• Usually precedes adjectives and the noun in English
• Central to noun-phrase structure